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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS -1963

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LEGAL NOTICE
This report was prepared as an account of
Government sponsored work. Neither the
United States, nor the Commission, nor any
person acting on behalf of the Commission:
A. Makes any warranty or representa-
tion, expressed or implied, with respect to
the accuracy, completeness, or usefulness
of the information contained in this report,
or that the use of any information, appa-
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B. Assumes any liabilities with respect
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the use of any information, apparatus,
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As used in the above, "person acting on
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employee of such contractor, to the extent
that such employee or contractor of the
Commission, or employee of such contractor
prepares, disseminates, or provides access
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Con 651101-17
SEP 1 6 1965
THOMAL STRESS CONSIDERATIONS
in the
MOLTEN SALT REACTOR EXPERIMENT*
Chailes H. Gabbard**
Reactor Division, ORAL, Oak Ridge, Tenues.ee
Alexander Houtzeel
EURATONI on loan to ORNL Reactor Division
.
The ulten Salt ficactor i3 & 10-10w experimental fluid-fueled
reactor which is designed to olerate at 1200°F. The reactor system
is fabricateå of Hastelloy "N" which at high tempera tuse has excellent
mechanical and corrosion properties. During operation the reactor 18
subjected to three types of operation which involve thermal cycling of
the equipment. In starting from cold conditions, the reactor system
is first electrically heated to 1200°F while circulating hellum. The
piping and equipient is then filled with salt at 1200°F and circulation
is started. Finally reactor power is raised to the operating level.
The system desigr. pressure 1s 50 psi and most of the component
wall thicinesses are re.latively thin and have fast temperature response
so that thermal stress is not a problem. However the fuel and coolant :
pumps, the freeze flanges, and the coolant piping penetrations through
the containment vessel wall were found to have relatively high thermal
RELEASED POR ANNOUNCEZENT
IN NUCLEAR SCIENCE AFSTRACTS
stresses. These stresses result from both high steady-state thermal
gradients and high thermal inertia which produces thermal stress during
temperature transients. The freeze flange design requires a steep
thermal gradient to produce a ring of frozen salt which seals the flange.
The fuel pump is also subjected to radiation heating. from the fuel salt
and from fission product gases released in the pump expansion chamber.
*Research sponsored by the USAEC under contract with Union Carbide Corpo-
ration.

“ANS paper sponsored by P. N. Haubenreich
- LEGAL NOTICE
The report wu papurod u nocou o correspondered with Mether the Ontw
Namo, nor the Commission, nor many porn netting a Wall Centendons
A. Makeo way warrior promotion, card or implied, ma pot do norte
rrey, completoww.ow oons of the wormation comes to reporting at alam
away formation, part, w ird, men derimod Momport may not merindo
potram med syntes or
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wang tertio, arm, metal, am decidir
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ployee or contracter of the Commission, or employee of such contractor, to the extent that
wool play or omtrector the C enter, tagus a mesa contratto per
desnudas, a mente nonne M, Ney Wormation para wa Maplegue a continet
ma de Document, or Memployment will rector.
bacim.caid
This heating causes changes in the temperature distribution as the
reactor power is changed.
The thermal stresses in these various components were all calcu-
lated by the same basic procedure. The temperature history of the
particular component was determined using a heat transfer computer
program or, in the case of the cell penetrations, by actually measuring
the temperature distributior.. The pump and cell penetration structures
were simulsted by connecting two cylinders and a conical shell at a
common joint, and the freeze flange structure was similated by connecting
a cylinder to a flat plate. The boundary conditions of the structure
and the compatibility conditions of the connection were described using
the equations of Stanek1:2,3 and Witt4,5 for the moments, membrane
forces, shear forces, deflections, and slopes of the various members.
These equations were solved simultaneously, and the stress profiles
for each member of the structure were then calculated using the resulting
coefficients and the above moment, membrane force, and shear force
equations.
The operating temperature of these components is in the creep
range, and the maximum stresses are in the plastic range so that the
life of the various components was based on low cycle fatigue. Although
the ASME Nuclear Code does not specifically apply, an effort was made
to comply with the intent of this code. The plastic stains were
evaluated for each type thermal cycle and the estimated number of cycles
to failure was obtained from thermal fatigue data. The permissible
numbers of cycles were obtained by applying a safety factor of ten to
the values obtained above. The life of each component was estimated
by the procedure outlined in the ASME Nuclear Code for accumulating the
effects of several types of cycles.
-3-
The original goal was to design for 100 heating and 500 power cycles.
With air cooling of the fuel pump bowl, the pumps met this criterion.6
The coolant piping penetrations were modified to reduce the thermal
gradients at the pipe connection after the calculations showed an
insulilcient life for the original design. In the freeze flanges, where
the steep thermal gredient is required, the calculations indicated a
life less than the lo heating cycles. However the life was stili
adequate for the projected MSRE operation. A test flange is being
thermal cycled to confirm the predicted life, and no damage is evident
after more than 100 cycles.
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nimese --.......
1.
F. J. Stanek, Stress Analysis of Cylindrical Shells,
ORNL CF 58-9-2 (July 22, 1959).
F. J. Stanek, Stress Analysis of Conical Shells,
1
2.
3.
ORNL CF 58-6-52 (August 28, 1958).
F. J. Stanek, Stress Analysis of Flat Circular Plates,
ORNL CF 57-11-111 (November 25, 1959).
F. J. Witt, Thermal Stress Analysis of Cylindrical Shells,
ORNL CF 59-1-33 (March 26, 1959).
F. J. Witt, Thermal Stress Analysis of Conical Shells,
4.
5.
ORNL CF 61-5-80 (July 7, 1961).
C. H. Gabbard, Thermal-Stress and Strain-Fatigue Analysis of the
.
MSRE Fuel and Coolant Pump Tanks, ORNL IM-78 (October 3, 1962).
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DATE FILMED
(10/ 20 / 65




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